Publikace ÚTF

Lynden-Bell, D., Bičák, J.

The mass per unit length of a cylindrical system can be found from its external metric as can its angular
momentum. Can the fluxes of energy, momentum, and angular momentum along the cylinder also be so
found? We derive the metric of a beam of circularly polarized electromagnetic radiation from the EinsteinMaxwell equations. We show how the uniform plane wave solutions miss the angular momentum carried
by the wave. We study the energy, momentum, angular momentum, and their fluxes along the cylinder both
for this beam and in general. The three Killing vectors of any stationary cylindrical system give three
Komar flux vectors which in turn give six conserved fluxes. We elucidate Komar’s mysterious factor 2 by
evaluating Komar integrals for systems that have no trace to their stress tensors. The Tolman-Komar
formula gives twice the energy for such systems which also have twice the gravity. For other cylindrical
systems their formula gives correct results.